To ensure that learners attend to the training, they will complete a comprehension quiz at the end. Learners see a picture (e.g., 3 cheap trucks) and must select the sentence in the AL that best describes it from among five options. Alongside the correct description of the picture (“The trucks are cheap”), the options include a sentence with a violation of gender agreement, a sentence with a number violation, and a sentence with a double violation (number and gender). In half of the items the violation is realized between the article and the noun and, in the other half, between the noun and the adjective. As a control, the fifth option involves a semantic violation (e.g., “The trucks are expensive”), to ensure that learners are able to extract meaning from the pictures used in the AL training. Filler items involve pictures which manipulate the location of two nouns (e.g., a key above a watch). Here, the possible responses include a sentence that correctly describes the picture (“The key is above the watch”), and four incongruent sentences. Two of the incongruent sentences involve the use of the wrong locative (e.g., “The key is below the watch,” “The watch is above the key”) and the other two involve the use of incorrect nouns. Upon providing their response, learners receive a “correct” or “incorrect” message, which is visually displayed on the computer screen. No other feedback is provided, to ensure that training in the AL remains as implicit as possible. The quiz includes an equal number of sentences with masculine and feminine nouns, and an equal number of sentences with singular and plural nouns. Each noun and adjective is tested an equal number of times throughout the quiz.

Learners are graduated from the training once they reach above chance accuracy in the quiz, which is defined as the ratio of correct responses to the total number of responses (i.e., 20% accuracy). Learners who score below this threshold must take the training again. This necessarily means that different learners will receive different amounts of training, but it ensures that learners have achieved approximately the same level of proficiency at the time of the EEG recording.

For the purposes of this task, the 12 nouns in each AL have been crossed with the 12 adjectives, yielding a total of 144 noun-adjective combinations. Those agreement dependencies have been embedded in sentences like the one in (7) below, which has six different versions. The sentence structure where we manipulate agreement is based on a previous study on number and gender agreement in Spanish by
Alemán Bañón et al. (2012
,
2014
). Examples are provided for a sentence with a masculine noun in Mini-Spanish.